Nice 5:1 gearbox

olaf-lampe

10 kW
Joined
Mar 27, 2008
Messages
710
Location
Germany
Since I'm building the electric pocket bike, I find some useful stuff coming from there.
Someone found a CVT-gearbox, but IMHO that's a bit overkill, since we don't have to worry about lack of torque.
Here's a small, light and tough looking 5:1 helical gearbox:View attachment 2gearbox open.jpggearbox on 120_70.jpg

I ordered some sprockets from 11 to 21 teeth And also two rear sprockets with 44 and 54 teeth. This way I can adapt it to any wheel size and topspeed I like. Slowest ratio would be 1:25 and fastest is 1:10
With the clutch I'm able to use a smaller and cheaper ESC without taking the risk of frying it at low RPMs.

-Olaf
I think of using a colossus 7kW with it and get rid of the giant hubmotor on my flevo bike. Who's with me? :)
 
thats a cool little umber, I have used the other type of gearbox on pocketbike motors pic below

this reduced RIGHT down, was good for 50km/h on a 15T - 52T combo direct drive to a 26" rear wheel with a pocket bike 47cc motor,

however I dont know exactly how to get a RC motor to marry up to the clutch bellhousing? does the one you found have a different configuration? or are you planning on attaching the pocketbike clutch to the rc motor shaft then to the gearbox? if so, great idea for a multi task unit, clutch, reduction all built in for $45AUD!!!

x1_pocketbike_cvt_logo.jpg
 
sorry to hijack..

the engines that are used for these gearboxes are max rpm is 9500rpm, clutch engage 4000rpm and motor usually idles at 3000rpm..

the little motors usually put out anything from 1kw to 5kw
 
katou said:
Where did that gearbox come from? Did it come with torque/rpm ratings?

Katou
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=170288047424&viewitem=&sspagename=STRK%3AMEWNX%3AIT

It is intendet to be used in dirtbikes. I guess it can take a punch or two. The output shaft is a roughly 15mm thick, the chaintype t8f, 8mm. Sprockets are 4mm thick
The inner diameter of the clutch bell is 78mm. A common pocketbike clutch will fit. It's not easy to mount the motor directly to the inputshaft, but if someone doesn't like the clutch he can adapt the motor to the bell.
-Olaf
 
There is also other gearbox (centrifugal clutch) with no reduction but with 6 to 9 tooth sprockets
http://cgi.ebay.com/6-T-Gear-Box-Clutch-Drum-47cc-49cc-Pocket-Bike-ATV-Quad-/150442303564?pt=UK_Motorcycle_Parts&hash=item23070f604c#ht_3144wt_1138

Clutch Pads Specifications working for all this (I think all 3 earlier described) gearboxes
http://tncscooters.com/product.php?sku=306195
Outer Diameter: 75.7 mm
Inner Diameter: 11.8 mm ( perfect for Turnigy motors with 12mm shaft)
And
http://tncscooters.com/product.php?sku=306190
Diameter: 75.5mm
Bolt hole spacing: 54mm (2 holes)

Can please some one confirm spacing between mounting holes of the gearbox?
 

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Hi parabellum,
you are right about the clutches, they are usually identical. Although I've seen clutches with 80mm inner diameter. Not easy to see on first sight.

The distance you've marked on the pic is 70.7mm. That sounds odd, but in fact the mounting holes are on a radius of 50mm from the center.
There are other clutches with a small cap above the sprocket. It contains a 3rd bearing which is very much recommended.
Be aware that those stand-alone clutches need different chains/sprockets than the gearbox. The gearbox comes with a 't8f' 8mm sprocket which is 4mm wide .
Another reason, why I think this gear can take a higher load than the usual pocketbike stuff.
-Olaf
 
olaf-lampe said:
The gearbox comes with a 't8f' 8mm sprocket which is 4mm wide .

Sorry Olaf, I am loosing it now and can not understand, is sprocket you described good for 40/41 ansi chain? If not, what chain can be used?
(I only understand ANSI and Motocicle/Bicicle numbers like 41 and 428)
 
parabellum said:
olaf-lampe said:
The gearbox comes with a 't8f' 8mm sprocket which is 4mm wide .

Sorry Olaf, I am loosing it now and can not understand, is sprocket you described good for 40/41 ansi chain? If not, what chain can be used?
(I only understand ANSI and Motocicle/Bicicle numbers like 41 and 428)
No, it's non of that. It's called t8f.t8f_chain.JPG
-Olaf
 
I made two new pictures of the gearbox mounted on the ca120-70 and took a video to demonstrate how easy the motor starts and while running faster the clutch engages softly. SCHWEET.
Unfortunately the sound got lost when I copied the video from phone to pc. It is tilted 90 degree, too :(
But at least here are the pics:ca120 w gearbox.jpgca120 w gearbox2.jpg

-Olaf

Anyway, here is the video.
http://www.youtube.com/watch?v=O0A58JsBWNo
 
WOw, great Idea! Look out gassers, here comes the poor man's E-Bike gear box! (On second thought) Don't go anywhere gassers! We need to keep moding your stuff for our E-Bikes! :oops: :mrgreen:

I'm definitely going to be watching this thread! For these prices, I might just run a gear box instead of a belt! 8)

The main thing that always kept me away from all the CNC goodies was price, what Turnigy motor & clutch are you using there? :shock: :shock: :shock:

(we REALLY need a "drool" icon for this one! :mrgreen: )
 
It's the BIGGEST turnigy : CA120-70.
I will probably not use the gearbox with that one, but with the colossus 7kW ( You can see the stators in the background ). But since the clutch diameter fits the gearbox; I took a video.
I made the nylon adapter and the struts myself. The struts have one flat side to clear the motorbell.
I got the aluminium plate CNC'd to fit common pocketbike clutches.
The gearbox has one drawback: the sprocket turns in the opposite direction than the motor. Therefor you have to use the clutch in the 'wrong' direction or you have to put the secondary drive on the right side of the wheel where you get in the way with the normal chain. ( different chaintype )
There are other gearboxes available that don't have this problem, but they are a bit longer and ( I guess ) chaindriven, which makes it a bit noisier?!
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=170283731305&viewitem=&sspagename=STRK%3AMEWAX%3AIT

-Olaf
 
olaf-lampe said:
The gearbox has one drawback: the sprocket turns in the opposite direction than the motor. Therefor you have to use the clutch in the 'wrong' direction or you have to put the secondary drive on the right side of the wheel where you get in the way with the normal chain. ( different chaintype )
Hi Olaf, thank you for sharing your work & test results. 8) We hope for the highest success. Is there any advantage or disadvantage to just reverse the motor direction, so the output sprocket turns in the direction you want? :idea:

Can't wait to see & hear some video too. :twisted: :mrgreen:

Is the reduction/clutch noise loud or very quiet compared to the RC motor noise?

Look forward to your testing to see how well this works with protecting the ESC. This seems to be a very low-cost solution to a big ES issue... getting a decent reduction for RC motor & using a clutch to protect the ESC.

Best high-quality solution for lowest price yet, RC Holy Grail, ehhh? :shock: :twisted:
 
deVries said:
olaf-lampe said:
The gearbox has one drawback: the sprocket turns in the opposite direction than the motor. Therefor you have to use the clutch in the 'wrong' direction or you have to put the secondary drive on the right side of the wheel where you get in the way with the normal chain. ( different chaintype )
Hi Olaf, thank you for sharing your work & test results. 8) We hope for the highest success. Is there any advantage or disadvantage to just reverse the motor direction, so the output sprocket turns in the direction you want? :idea:

Can't wait to see & hear some video too. :twisted: :mrgreen:

Is the reduction/clutch noise loud or very quiet compared to the RC motor noise?

Look forward to your testing to see how well this works with protecting the ESC. This seems to be a very low-cost solution to a big ES issue... getting a decent reduction for RC motor & using a clutch to protect the ESC.

Best high-quality solution for lowest price yet, RC Holy Grail, ehhh? :shock: :twisted:

Yes! We have come for the grail!! :D

[youtube]9V7zbWNznbs[/youtube]
 
I'm not sure what'd happen when the clutch arms are pushed to the bell when running backwards. It makes no sense to test it without load, so we have to wait a bit.
My best guess is, that it will block much easier while driving at the clutches torque limit. If this would happen, either the clutch arm shafts would brake or the controller would see a huge torque/current ripple.

I'm not sure if we found the holy grail yet, since the torque is now limitted by the clutch. I'm already thinking of an easy way to make the arm heavier. This way the clutch would engage earlier and friction would be higher.

Happy new year ES :D
-Olaf
 
Happy new year,
regarding reversing directions on the clutch shoes. It should pose no issue (mechanicly speaking) its a common configuration with the Karting crowd. set up like that its called "leading shoe" here is an example:
scroll down & look at the "blaze" model
http://www.hilliardextremeduty.com/infernokart/
it is a tuning tool to get the clutch to react for a particular gearing set up or just driver preferance.
 
Thanks Thud,
good to know, it add no problems. But I'm still couriuos what is the difference. I hope it helps increasing the friction because now it is quite low. On 36V and wired in wye the motor takes only 650W when I block the sprocket. That indicates the clutch is not fully engaged at 3100RPM. I'm now in the shop and try to add more weight to the arms.
Anyway, this is how they look now:
I removed the springs and replaced them with pieces of foamrubber. I also drilled a M5 thread in the middle of the arm and added a short allen screw to increase weight. Not enough, as I know now... :(

clutch before-after.jpg
clutch after2.jpg

-Olaf
 
OK, i added two pieces of M10 thread to each arm. At home, I'll do the blocked sprocket test again and check the difference.
I also think a clutch needs a while before the contact is best. I've only seen small patches on the pads that looked 'used' so far.
I'll try to take a video, but beside the smell off burned clutchpads there is not much to show. I tried earlier to capture the readings from the turnigy wattmeter but it didn't work well.

clutch heavy.jpg
clutch heavy2.jpg

-Olaf
 
olaf-lampe said:
I made two new pictures of the gearbox mounted on the ca120-70 and took a video to demonstrate how easy the motor starts and while running faster the clutch engages softly. SCHWEET.
Unfortunately the sound got lost when I copied the video from phone to pc. It is tilted 90 degree, too :(
But at least here are the pics:View attachment 1

-Olaf

Anyway, here is the video.
http://www.youtube.com/watch?v=O0A58JsBWNo

Olaf , one question since we have similiar motors . Mine is going on mtb. DId you make estra bearing on the plastic part for shaft support . Second : Why didnt you put gearbox on the other part of the motor where it has skirt bearing and "normal " bearing support ? Because of centrifugal forces i think it would be better, but if you made bearing in plactic part ,then this does not apply ...
 
Marco,
I don't trust the connection between motorbell and shaft very much. Therefor I connected the clutch directly with the bell. There will be no radial forces on the bell or on the motorshaft, the whole forces are going into the clutch-housing and the 10mm aluminium plate. Only torsional forces are led through the four aluminium struts to the rear motorplate.
-Olaf
 
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